Percolating Cluster Devices

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When clusters (nanoparticles) are randomly deposited on a surface they produce percolating films which have remarkable electrical properties. [1] Here we will focus on devices that contain percolating films of Sn and Pb clusters, and especially those that are deliberately constructed so as to guarantee that the film is close to the percolation threshold (onset of conduction). In these devices quantum mechanical tunnelling is important [2], and several new and unexpected phenomena are observed. In particular we have recently demonstrated switching between well-defined, quantized, conductance values [multiples of the quantum of conductance (2e2/h)], at room temperature. [3]

More recently we have begun exploring the superconducting properties of these films. We find that the percolating films have interesting characteristics that are intermediate between those of 1D and 2D systems, and a superconductor to insulator transition which can be driven by the applied current.